1. Field of the Invention
The present invention relates to developer producing equipment and a developer producing method, and more particularly to equipment which is connected via piping to working equipment in which electronic circuits are formed, on which fine working is performed and which manufactures an alkali type developer that is used to develop photoresists or the like in the abovementioned working equipment, and a method for manufacturing this alkali type developer.
2. Description of the Related Art
Generally, resist materials used in photolithographic processes in the manufacture of devices such as electronic devices or the like that have electronic circuits on which fine working is performed include positive type materials that are solubilized by exposure to light, and negative type materials that are insolubilized by exposure to light. As one example, in the manufacture of semiconductor devices, flat panel display (FPD) substrates and the like, such photo-etching is repeatedly performed; accordingly, mainly positive type resists are commonly used.
Aqueous solutions of inorganic alkalies consisting of sodium phosphate, caustic soda, sodium silicate or mixtures of these substances with other inorganic alkalies or the like may be cited as examples of developer materials for positive type resists. Furthermore, in cases where contamination by alkali metals is a concern, aqueous solutions of amine type organic alkalies that contain no metals, aqueous solutions of tetramethylammonium hydroxide (TMAH), aqueous solutions of trimethylmonoethanolammonium hydrochloride (choline) or the like are used. Among the latter materials, an aqueous solution of TMAH with a concentration of 2.38% are widely used.
Furthermore, developers prepared from these materials are used in large quantities in developing devices using a spray system, spin-coating system, dipping system or the like.
In developers used on photo-resists, the composition and concentration of the developer must be strictly controlled in order to obtain the maximum resolution, patterning sharpness (sharpness), stability and high yield in accordance with the developing process.
In particular, as the density of patterning has increased in recent years, there has been a demand for finer patterning widths. For example, in the case of semiconductor substrates, a demand has appeared for line widths on the 0.1 xcexcm level; furthermore, in the case of flat panel display substrates, there is now a demand for line widths on the 1 xcexcm level, and in the case of multi-layer printed circuit boards, there is a demand for line widths on the 10 xcexcm level. Furthermore, there is now a demand for line widths of 1 xcexcm or less in order to incorporate semiconductor circuits into flat panel display substrates using low-temperature polycrystalline silicon TFT techniques.
Consequently, there is a strong demand for improved precision of developer concentrations in order to reduce the variation in the effective sensitivity of photo-resists. For example, a range of values that deviate from the specified concentration by xc2x1{fraction (1/1000)} or less is required as the control range of the developer concentration. Especially in the case of an aqueous solution of TMAH, a range of values that deviate from the specified concentration by xc2x1{fraction (1/2000)} or less (for example, 2.380xc2x10.001 wt %) is required.
Furthermore, in order to eliminate patterning defects, it is required that various developers contain extremely few particles, i.e. there must be 10 or fewer particles with a size of 0.1 xcexcm or greater per milliliter of developer.
In recent years, moreover, there has been a further increase in the amount of developer used as a result of increased size and increased mass production of substrates.
Thus, along with a sharp demand for improved precision in developer concentrations and demand for particle-free developers, there has been a strong demand for measures to facilitate mass production and reduce cost.
In the case of conventional techniques, however, adjustment of the composition and concentration of developers in manufacturing plants for semiconductor devices and the like has been extremely difficult, not only in terms of equipment and operating costs, but also from the standpoint of sufficient control of the composition and concentration of the developers.
Accordingly, it has been unavoidably necessary in manufacturing plants for semiconductor devices and the like (hereafter referred to as the xe2x80x9cuse sidexe2x80x9d) to use developers whose composition and concentration have been adjusted exclusively by the developer makers (hereafter referred to as the xe2x80x9csupply sidexe2x80x9d).
In such cases, a method is used in which a developer stock solution that has been prepared with a specified composition is diluted with pure water on the supply side, the developer thus adjusted to a specified concentration is placed in containers, and this adjusted developer is supplied to the use side.
In this case, the dilution factor of the developer stock solution varies according to the solution composition and stock solution concentration, the type of positive resist or the like that is the object of development, and the intended use. Ordinarily, the stock solution is diluted by approximately 8 to 40 times. Accordingly, the amount of developer prepared on the supply side is greatly increased in accordance with the dilution factor, thus resulting in an increase in the work involved in preparing containers and filling containers for the shipping of the developer to the use side, and an increase in shipping costs. As a result, such expenses account for a considerable portion of the cost of the developer.
Furthermore, a commensurate amount of time is required for shipping and storage until the developer prepared on the supply side can be used on the use side, and the developer deteriorates during this period.
Moreover, since developers tend to absorb carbon dioxide gas from the air, variations in concentration caused by the absorption of carbon dioxide gas occur during the dilution operation and the storage of the diluted developer even if a dilution apparatus is installed on the use side. This may also be cited as one of the reasons why the dilution of developers has not been performed on the use side in semiconductor device manufacturing plants or the like.
In order to solve these problems, a developer dilution apparatus comprising an agitating tank into which a photo-resist alkali type developer stock solution and pure water are introduced and subjected to forced agitation for a specified period of time, conductivity measuring means for extracting a portion of the mixture in the agitating tank, measuring the conductivity of this mixture and then returning the mixture to the agitating tank, control means for controlling either the photo-resist alkali type developer stock solution or pure water that is supplied to the agitating tank on the basis of the output signal from the conductivity measuring means, a storage tank into which the mixture from the agitating tank is introduced, and in which this mixture is stored, and nitrogen gas sealing means for sealing the agitating tank and storage tank with nitrogen gas, is disclosed in Japanese Patent No. 2751849.
This apparatus makes it possible to prepare the developer on the use side by mixing the developer stock solution and pure water. As a result, problems in terms of the control of the composition and concentration of the developer, and the conventional problem of increased shipping cost of the developer, are more or less solved.
In recent years, however, in response to market demands, it has become necessary to manufacture various types of substrates and the like in small lots. Accordingly, it has become necessary to install a plurality of substrate manufacturing apparatuses on the use side in order to handle such manufacture of various types of substrates in small lots, and to operate these apparatuses simultaneously. In some cases, furthermore, the concentrations of the developers used in these respective apparatuses vary over a broad range, e.g., from 0.1% to 2.5%, so that developers of various concentrations must be prepared for each use.
Accordingly, the present invention was devised in light of the abovementioned facts; it is an object of the present invention to provide developer producing equipment and a developer producing method which make it possible to produce a developer on the use side with a prescribed concentration from a developer stock solution quickly and with good precision, and which can sufficiently handle the manufacture of various types of substrates in small lots, and to control the composition and concentration of the developer that is produced with good precision.
In order to solve the abovementioned problems, the developer producing equipment of the present invention is equipment which is connected via piping to working equipment in which electronic circuits are formed, on which fine working is performed, and which produces an alkali type developer that is used in this working equipment, and comprises: a preparation tank to which a developer stock solution and pure water are supplied and subjected to agitation, and in which an alkali type developer is prepared; first liquid amount measuring means for measuring the amount of alkali type developer in the preparation tank; first alkali concentration measuring means for measuring the alkali concentration of the alkali type developer in the preparation tank; first liquid amount control means for adjusting the amount of alkali type developer in the preparation tank on the basis of the measured value obtained by the first liquid amount measuring means and the measured value obtained by the first alkali concentration measuring means; and liquid supply control means for adjusting the amount of developer stock solution that is supplied to the preparation tank or the amount of pure water that is supplied to the preparation tank, or both, on the basis of the measured value obtained by the first liquid amount measuring means and the measured value obtained by the first alkali concentration measuring means.
In the developer producing equipment constructed in this manner, the developer stock solution is diluted with pure water in the preparation tank so that a developer is prepared. At this time, the amount of liquid in the preparation tank and the concentration of the alkali constituting the developer component in the preparation tank are measured, and the liquidity is adjusted by the first liquid amount control means and the liquid supply control means on the basis of these measurements so that the developer has the desired concentration. Accordingly, the concentration can be adjusted quickly and easily, and concentration control can be accomplished with good precision.
Furthermore, since the developer thus prepared with the desired concentration can be supplied to working equipment via piping, separate piping or shipping costs are eliminated. Moreover, if the developer preparation apparatus, including the piping connected to the working equipment, is constructed as a system that is substantially sealed off from the atmosphere, deterioration of the developer caused by the absorption of carbon dioxide gas and the like in the atmosphere by the developer can be suppressed.
Furthermore, it is desirable that the developer producing equipment of the present invention be equipped with a leveling tank which is disposed between the preparation tank and the abovementioned working equipment, and which evens out the alkali concentration of the alkali type developer. If this is done, the alkali concentration in the developer, which has a slight error that is unavoidably generated, can be evened out so that the precision of the developer concentration is greatly improved.
In concrete terms, the leveling tank is equipped with second liquid amount measuring means for measuring the amount of alkali type developer in the leveling tank.
Furthermore, it is desirable that the leveling tank be equipped with second alkali concentration measuring means for measuring the alkali concentration of the alkali type developer in the leveling tank.
Moreover, it is ideal if the leveling tank is equipped with second liquid amount control means for adjusting the amount of alkali type developer in the leveling tank on the basis of the measured value obtained by the second liquid amount measuring means and the measured value obtained by the second alkali concentration measuring means.
Furthermore, it is desirable that circulation feeding piping that feeds the alkali type developer in the leveling tank back into the preparation tank be provided.
More concretely, the leveling tank is equipped with an agitation mechanism that agitates the alkali type developer in the leveling tank.
Even more concretely, the leveling tank is equipped with a filtration mechanism that filters the alkali type developer in the leveling tank.
More concretely still, it is useful if liquid feed/liquid surface level control means for feeding the alkali type developer into the abovementioned leveling tank from the preparation tank and adjusting the liquid surface level of the alkali type developer in the preparation tank and the liquid surface level of the alkali type developer in the leveling tank are provided. These liquid surface levels are adjusted to arbitrary levels; however, it is useful if both levels are adjusted so that these levels are substantially the same.
In this case, it is even more desirable if the liquid feed/liquid surface level control means have communicating piping which is connected to the preparation tank and leveling tank, and which is such that the alkali type developer is naturally fed into the leveling tank from the preparation tank.
Moreover, it is desirable that a storage tank which is disposed between the leveling tank and the working equipment, and which stores the alkali type developer, be provided.
Moreover, it is even more desirable if the developer producing equipment is equipped with wet nitrogen sealing means for sealing the preparation tank and leveling tank with wet nitrogen gas.
A system which has a plurality of preparation tanks is also useful.
Alternatively, the preparation tank and leveling tank may also be constructed as an integral unit.
Furthermore, it is even more useful if fine particle number measuring means that measure the number of fine particles contained in the alkali type developer in the state prior to supply thereof to the working equipment are provided.
Even more preferably, dissolved gas removal means that remove the dissolved gas contained in the alkali type developer are provided.
It is especially desirable that the first liquid amount measuring means measure either the volume or the weight of the alkali type developer, or both.
Alternatively, it is also desirable that the first alkali concentration measuring means be at least one of the following devices: a conductivity meter, an ultrasonic concentration meter, a liquid density meter or an automatic titration device.
Similarly, it is desirable that the second alkali concentration measuring means be at least one of the following: a conductivity meter, an ultrasonic concentration meter, a liquid density meter or an automatic titration device.
More concretely, the developer stock solution has a discretionary alkali concentration selected from a specified range of alkali concentrations.
Furthermore, the developer producing method of the present invention is a method that produces an alkali type developer that is supplied via piping to a working process that forms electronic circuits on which fine working is performed, comprising the steps of preparing an alkali type developer by agitating a developer stock solution and pure water, measuring the amount of the alkali type developer, measuring the alkali concentration of the alkali type developer, adjusting the amount of the alkali type developer on the basis of the measured value of the liquid amount of the alkali type developer and the measured value of the alkali concentration of the alkali type developer, and adjusting either the amount of developer stock solution that is supplied to the step of preparing the alkali type developer or the amount of the abovementioned pure water that is supplied to the step of preparing the alkali type developer, or both, on the basis of the measured value of the liquid amount of the alkali type developer and the measured value of the alkali concentration of the alkali type developer.